1. Articles from Tien Yin Wong

    1-24 of 27 1 2 »
    1. Artificial Intelligence in Diabetic Eye Disease Screening

      Artificial Intelligence in Diabetic Eye Disease Screening

      Systematic or national screening programs for diabetic retinopathy (DR) and diabetic macular edema (DME), using digital fundus photography and optical coherence tomography (OCT), are currently implemented at primary care level, aiming to provide timely referral for vision-threatening DR and DME to ophthalmologists for timely treatment and vision loss prevention. However, interpretation of retinal images requires specialized knowledge and expertise in diabetic eye disease. Furthermore, current DR screening programs are capital- and labor-intensive, which makes it difficult to rapidly scale up and expand diabetic eye screening to meet the needs of this growing global epidemic. Deep learning (DL), a new branch ...

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    2. Impact of systemic vascular risk factors on the choriocapillaris using optical coherence tomography angiography in patients with systemic hypertension

      Impact of systemic vascular risk factors on the choriocapillaris using optical coherence tomography angiography in patients with systemic hypertension

      We investigated the characteristics of the choriocapillaris flow voids using optical coherence tomography angiography (OCTA) in 85 patients (164 eyes) with hypertension (mean ± SD age, 56 ± 11 years; 45% women; 20% poorly controlled BP; 16% diabetes) who are without ocular diseases and determined possible correlations with systemic vascular risk factors. Data on 24-hour ambulatory blood pressure (BP), serum creatinine, and urine microalbumin/creatinine ratio (MCR) were collected. Estimated glomerular filtration rate (eGFR) was calculated based on CKD-EPI Creatinine Equation. OCTA imaging (6 × 6 mm scans; AngioVue) with quantitative microvascular analysis of the choriocapillaris was performed. Linear regression was used to ...

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    3. Artificial intelligence and deep learning in ophthalmology

      Artificial intelligence and deep learning in ophthalmology

      Artificial intelligence (AI) based on deep learning (DL) has sparked tremendous global interest in recent years. DL has been widely adopted in image recognition, speech recognition and natural language processing, but is only beginning to impact on healthcare. In ophthalmology, DL has been applied to fundus photographs, optical coherence tomography and visual fields, achieving robust classification performance in the detection of diabetic retinopathy and retinopathy of prematurity, the glaucoma-like disc, macular oedema and age-related macular degeneration. DL in ocular imaging may be used in conjunction with telemedicine as a possible solution to screen, diagnose and monitor major eye diseases for ...

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    4. Correlation of Color Fundus Photograph Grading with Risks of Early Age-related Macular Degeneration by using Automated OCT-derived Drusen Measurements

      Correlation of Color Fundus Photograph Grading with Risks of Early Age-related Macular Degeneration by using Automated OCT-derived Drusen Measurements

      We evaluated automated OCT-derived drusen volume measures in a population-based study (n = 4,512) aged ≥40 years, and its correlation with conventional color fundus photographs (CFP)-derived early AMD features. Participants had protocol-based assessment to capture medical and ocular history, genotyping for SNPs in CFH , ARMS2 , and CETP , CFP-based AMD grading and automated drusen volume based on SD-OCT using built-in software (Cirrus OCT advanced RPE analysis software). Significantly fewer eyes with early AMD features (drusen, hyperpigmentation, soft or reticular drusen) had drusen volume = 0 mm 3 (p < 0.001). In eyes with drusen volume > 0 mm 3 , increasing AMD severity ...

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    5. Comparison Of Optical Coherence Tomography Angiographic Changes After Anti–Vascular Endothelial Growth Factor Therapy Alone Or In Combination With Photodynamic Therapy In Polypoidal Choroidal Vasculopathy

      Comparison Of Optical Coherence Tomography Angiographic Changes After Anti–Vascular Endothelial Growth Factor Therapy Alone Or In Combination With Photodynamic Therapy In Polypoidal Choroidal Vasculopathy

      Purpose: To compare changes in optical coherence tomography angiography in eyes with polypoidal choroidal vasculopathy after treatment with anti–vascular endothelial growth factor monotherapy or combined with photodynamic therapy . Methods: This is a longitudinal case-controlled study. The authors performed optical coherence tomography angiography at baseline and Month 3 in patients with treatment-naive polypoidal choroidal vasculopathy undergoing monotherapy (n = 10) or combination therapy (n = 13). We analyzed flow signal within the outer retina and choriocapillaris using automated segmentation. The authors analyzed the presence of pachyvessels using a 10.4- μ m segment through Haller layer . The changes in each layer were compared ...

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    6. Clinical Use of Optical Coherence Tomography Angiography in Diabetic Retinopathy Treatment Ready for Showtime?

      Clinical Use of Optical Coherence Tomography Angiography in Diabetic Retinopathy Treatment Ready for Showtime?

      Diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) are the 2 advanced stages of diabetic retinopathy (DR) that are the main causes for visual loss in patients with diabetes. Both DME and PDR can be readily diagnosed with clinical examination and, increasingly, by the noninvasive use of optical coherence tomography. However, another, less commonly recognized cause of visual loss in patients with diabetes is diabetic macular ischemia (DMI) in the absence of DME. 1 The understanding of the natural history, risk factors, and functional outcomes of DMI remains limited. This is partly because of the long-standing need for invasive ...

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    7. Identification of imaging features that determine quality and repeatability of retinal capillary plexus density measurements in OCT angiography

      Identification of imaging features that determine quality and repeatability of retinal capillary plexus density measurements in OCT angiography

      Purpose Optical coherence tomography angiography (OCT-A) potentially allows for rapid and non-invasive quantification of retinal capillary plexus density in various disease states. This study aims to identify the key features that influenced the repeatability of OCT-A measurements. Methods We obtained OCT-A images on two separate visits in 44 healthy eyes from 44 subjects, each imaged with using the Topcon DRI OCT Triton imaging system. The parafoveal vessel density within a 1.5 mm radius centred over the fovea was obtained with the built-in tool for the superficial and deep retinal plexuses. Repeatability of vessel density was determined by intraclass correlation ...

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    8. Repeatability and Reproducibility of Retinal Neuronal and Axonal Measures on Spectral-domain Optical Coherence Tomography in Patients with Cognitive Impairment

      Repeatability and Reproducibility of Retinal Neuronal and Axonal Measures on Spectral-domain Optical Coherence Tomography in Patients with Cognitive Impairment

      Background: With increasing interest in determining if measurement of retinal neuronal structure with spectral-domain optical coherence tomography (SD-OCT) is useful in accessing neurodegenerative process in cognitive decline and development of dementia, it is important to evaluate whether the SD-OCT measurements are repeatable and reproducible in patients with Alzheimer’s disease (AD) or mild cognitive impairment (MCI). Methods: This is a retrospective cohort study. Patients with AD or MCI with no change in global clinical dementia rating (CDR) score at 1-year follow-up were eligible to be included. (GC-IPL) Macular ganglion-cell inner plexiform layer (GC-IPL) and peripapillary retinal nerve fiver layer (RNFL ...

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    9. COMPARISON OF OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHIC CHANGES AFTER ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR THERAPY ALONE OR IN COMBINATION WITH PHOTODYNAMIC THERAPY IN POLYPOIDAL CHOROIDAL VASCULOPATHY

      COMPARISON OF OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHIC CHANGES AFTER ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR THERAPY ALONE OR IN COMBINATION WITH PHOTODYNAMIC THERAPY IN POLYPOIDAL CHOROIDAL VASCULOPATHY

      Purpose: To compare changes in optical coherence tomography angiography in eyes with polypoidal choroidal vasculopathy after treatment with anti-vascular endothelial growth factor monotherapy or combined with photodynamic therapy. Methods: This is a longitudinal case-controlled study. The authors performed optical coherence tomography angiography at baseline and Month 3 in patients with treatment-naive polypoidal choroidal vasculopathy undergoing monotherapy (n = 10) or combination therapy (n = 13). We analyzed flow signal within the outer retina and choriocapillaris using automated segmentation. The authors analyzed the presence of pachyvessels using a 10.4-[mu]m segment through Haller layer. The changes in each layer were compared ...

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    10. Factors affecting signal strength in spectral-domain optical coherence tomography

      Factors affecting signal strength in spectral-domain optical coherence tomography

      Purpose To identify ocular factors that affect signal strength in spectral-domain optical coherence tomography (SD-OCT). Methods Data from 1312 participants of the population-based Singapore Malay Eye Study-2 (SiMES-2) were included in the analysis. All participants underwent standardized ophthalmic examination, including measurements of best-corrected visual acuity (BCVA), refractive error, axial length, corneal curvature and presence of cataracts. Optic disc and macular cube scans were acquired using the Cirrus HD-OCT (software version 6.0, Carl Zeiss Meditec, Dublin, CA, USA). Signal strength of the optical coherence tomography (OCT) scan was recorded for each study eye. Multivariable linear regression analyses were performed to ...

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    11. Artificial Intelligence With Deep Learning Technology Looks Into Diabetic Retinopathy Screening

      Artificial Intelligence With Deep Learning Technology Looks Into Diabetic Retinopathy Screening

      D iabetic retinopathy is a leading cause of vision loss in the United States and globally, particularly among working-aged individuals. Diabetic retinopathy meets all the criteria for screening: first, the condition (diabetic retinopathy) is an important public health care problem; second, the epidemiology and natural history of the condition, including development from asymptomatic latent to severe disease, are adequately understood; third, the screening test (retinal photography) is simple, safe, validated, and acceptable; and fourth, an effective treatment (intravitreous injections of anti–vascular endothelial growth factor or laser therapy for severe diabetic retinopathy or diabetic macular edema [DME]) is available for ...

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    12. CHARACTERIZATION AND DIFFERENTIATION OF POLYPOIDAL CHOROIDAL VASCULOPATHY USING SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      CHARACTERIZATION AND DIFFERENTIATION OF POLYPOIDAL CHOROIDAL VASCULOPATHY USING SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      Purpose: To determine the correlation and agreement between swept-source optical coherence tomography angiography (SS-OCT-A) with fluorescein angiography (FA), indocyanine green angiography (ICGA) and spectral domain OCT (SD-OCT) in characterizing polypoidal choroidal vasculopathy (PCV) and in differentiating eyes with typical age-related macular degeneration (t-AMD). Methods: This study included 32 and 54 eyes with t-AMD and PCV, respectively, who underwent SS-OCT-A, SD-OCT, fluorescein angiography, and indocyanine green angiography. The images from these four techniques were compared. Results: On SS-OCT-A, flow signals with vascular network configuration were detected in 81.2% and 77.8% of eyes with t-AMD and PCV, respectively. 40.4 ...

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      Mentions: Tien Yin Wong
    13. Retinal Imaging Techniques for Diabetic Retinopathy Screening

      Retinal Imaging Techniques for Diabetic Retinopathy Screening

      Due to the increasing prevalence of diabetes mellitus, demand for diabetic retinopathy (DR) screening platforms is steeply increasing. Early detection and treatment of DR are key public health interventions that can greatly reduce the likelihood of vision loss. Current DR screening programs typically employ retinal fundus photography, which relies on skilled readers for manual DR assessment. However, this is labor-intensive and suffers from inconsistency across sites. Hence, there has been a recent proliferation of automated retinal image analysis software that may potentially alleviate this burden cost-effectively. Furthermore, current screening programs based on 2-dimensional fundus photography do not effectively screen for ...

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    14. Repeatability of Perimacular Ganglion Cell Complex Analysis with Spectral-Domain Optical Coherence Tomography

      Repeatability of Perimacular Ganglion Cell Complex Analysis with Spectral-Domain Optical Coherence Tomography

      Purpose. To assess the repeatability of spectral-domain optical coherence tomography to measure macular and perimacular ganglion cell complex thicknesses and compare retinal ganglion cell parameters between algorithms. Methods. Ninety-two nonglaucomatous eyes from 92 participants underwent macular and perimacular ganglion cell complex thickness measurement using OCT-HS100 Glaucoma 3D algorithm and these measurements were repeated for 34 subjects. All subjects also had macular ganglion cellinner plexiform layer thickness measured by Cirrus HD-OCT Ganglion Cell Analysis algorithm. Intraclass correlation coefficient and Pearson’s correlation analyses were performed. Results. Subfields of both macular and perimacular ganglion cell complex thicknesses had high intraclass correlation coefficient ...

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    15. Corneal graft evaluation based on optical coherence tomography image

      Corneal graft evaluation based on optical coherence tomography image

      An OCT image of an eye which has been subject to a DSAEK corneal transplant, in which a Descement's membrane in the cornea has been replaced by a graft, is processed to identify the outline of the graft. The process includes the steps of: computationally extracting the boundary of the cornea including the graft; computationally detecting the corners of the graft; computationally extracting points on the boundary between the graft and the original cornea; and computationally fitting the points on the boundary between the graft and the original cornea smoothly into a curve. The outline of the graft is ...

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    16. Retinal neurodegeneration on optical coherence tomography and cerebral atrophy

      Retinal neurodegeneration on optical coherence tomography and cerebral atrophy

      Neurodegeneration in dementia is mainly evaluated by assessing cerebral atrophy, while retinal neurodegeneration can be quantified in vivo using optical coherence tomography (OCT). We examined the association of retinal nerve fibre layer (RNFL) and ganglion cell-inner plexiform layer (GC–IPL) thinning with global and regional cerebral atrophy on magnetic resonance imaging (MRI). Malay participants aged 60–80 years from the Epidemiology of Dementia in Singapore Study underwent comprehensive examinations, including 3-Tesla cranial MRI. RNFL and GC-IPL thicknesses were obtained from spectral domain-OCT; and cerebral grey and white matter volumes were obtained from MRI scans using a validated segmentation tool. Linear ...

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    17. Potential Applications of Spectral-Domain Optical Coherence Tomography (SD-OCT) in the Study of Alzheimer’s Disease

      Potential Applications of Spectral-Domain Optical Coherence  Tomography (SD-OCT) in the Study of Alzheimer’s Disease

      Alzheimer’s Disease (AD) is the most common subtype of dementia. As the prevalence of dementia is projected to increase, the burden of the disease on society is expected to become increasingly significant. The link between eye pathology and neurodegenerative diseases has been established in multiple studies. In particular, optic nerve parameters associated with neuronal loss in AD include retinal ganglion cells (RGC). Retinal ganglion cells are similar to neurons in the cerebral cortex, and have been correlated to neurodegeneration in AD. Ocular imaging techniques such as optical coherence tomography (OCT) have provided a rapid and non-invasive method for quantifying ...

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    18. Determinants of Macular Thickness using Spectral Domain Optical Coherence Tomography in Healthy Eyes: the Singapore Chinese Eye Study

      Determinants of Macular Thickness using Spectral Domain Optical Coherence Tomography in Healthy Eyes: the Singapore Chinese Eye Study

      Purpose:To determine ocular and systemic factors influencing macular thickness measured by SD-OCT in a population-based sample of healthy eyes. Methods:490 Chinese adults aged 40 to 80 years were recruited from the Singapore Chinese Eye Study. All participants underwent a comprehensive eye examination and a standardized interview. SD-OCT (Cirrus HD-OCT, software version 6.0, Carl Zeiss Meditec, Dublin, CA) measured a range of macular thickness parameters (central foveal subfield thickness, average inner macular thickness, average outer macular thickness, overall average macular thickness and overall macular cube volume). Linear regression analyses were performed to examine the effects of various ocular ...

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    19. Comparison of Anterior Segment Optical Tomography Parameters Measured Using a Semi-Automatic Software to Standard Clinical Instruments

      Comparison of Anterior Segment Optical Tomography Parameters Measured Using a Semi-Automatic Software to Standard Clinical Instruments

      by Marcus Ang, Wesley Chong, Huiqi Huang, Wan Ting Tay, Tien Yin Wong, Ming-Guang He, Tin Aung, Jodhbir S. Mehta Objective To compare anterior segment parameters measured using a semi-automatic software (Zhongshan Angle Assessment Program, ZAP) applied to anterior segment optical coherence tomography (AS-OCT) images, with commonly used instruments. Methods Cross-sectional study of a total of 1069 subjects (1069 eyes) from three population-based studies of adults aged 40–80 years. All subjects underwent AS-OCT imaging and ZAP software was applied to determine anterior chamber depth (ACD), central corneal thickness (CCT), anterior and keratometry (K) – readings. These were compared to auto-refraction ...

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    20. Relationship Between Intraocular Pressure and Angle Configuration: An Anterior Segment OCT Study

      Relationship Between Intraocular Pressure and Angle Configuration: An Anterior Segment OCT Study

      Purpose: To assess the relationship between intra-ocular pressure (IOP) and anterior chamber angle (ACA) configuration as assessed by gonioscopy and anterior segment optical coherence tomography (AS-OCT). Methods: 2045 subjects aged 50 years and over, recruited from a community clinic, underwent AS-OCT, Goldmann applanation tonometry, and gonioscopy. A quadrant was classified as closed on gonioscopy if the posterior trabecular meshwork could not be seen. A closed quadrant on AS-OCT was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. Customized software (Zhongshan Angle Assessment Program, Guangzhou, China) was used to measure AS-OCT ...

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    21. Anterior Chamber Dimensions and Posterior Corneal Arc Length in Malay Eyes: An Anterior segment Optical Coherence Tomography Study

      Anterior Chamber Dimensions and Posterior Corneal Arc Length in Malay Eyes: An Anterior segment Optical Coherence Tomography Study

      Purpose: To provide normative data of corneal and anterior segment dimensions and a novel parameter, PCAL, in an adult Malay population. Methods: The current analysis is a sub-study of the Singapore Malay Eye Study (SiMES), a cross-sectional, population-based study of urban Malays aged 40-80 years. Subjects underwent ophthalmic and systemic examination, including imaging with anterior segment optical coherence tomography (AS-OCT). Ocular parameters were subsequently measured with the Zhongshan Assessment Program (ZAP): Anterior chamber depth (ACD), central corneal thickness (CCT), anterior and posterior corneal curvature (ACC and PCC), and posterior corneal arc length (PCAL), which is a novel parameter defined as ...

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    22. Corneal Graft Evaluation Based On Optical Coherence Tomography Image

      Corneal Graft Evaluation Based On Optical Coherence Tomography Image

      An OCT image of an eye which has been subject to a DSAEK corneal transplant, in which a Descement's membrane in the cornea has been replaced by a graft, is processed to identify the outline of the graft. The process includes the steps of: computationally extracting the boundary of the cornea including the graft; computationally detecting the corners of the graft; computationally extracting points on the boundary between the graft and the original cornea; and computationally fitting the points on the boundary between the graft and the original cornea smoothly into a curve. The outline of the graft is ...

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    23. Anterior Segment Optical Tomography Study of the Cornea and Anterior Segment in Adult Ethnic South Asian Indian Eyes

      Anterior Segment Optical Tomography Study of the Cornea and Anterior Segment in Adult Ethnic South Asian Indian Eyes

      Purpose. To report normative results of anterior segment and corneal biometric parameters and their associations in ethnic South Asian Indian adults. Methods. The Singapore Indian Eye Study (SINDI) is a cross-sectional, population-based study of ethnic South Asian Indians aged 40-80 years. Subjects underwent ophthalmic and systemic examination, including imaging with anterior segment optical coherence tomography (AS-OCT). Parameters were derived using the Zhongshan Assessment Program (ZAP): anterior chamber depth (ACD), central corneal thickness (CCT), anterior and posterior corneal curvatures (ACC and PCC). Posterior corneal arc length (PCAL) is a novel parameter defined as the arc distance between scleral spurs on the ...

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    24. Automated Layer Segmentation of Optical Coherence Tomography Images

      Automated Layer Segmentation of Optical Coherence Tomography Images
      Under the framework of computer-aided diagnosis, optical coherence tomography (OCT) has become an established ocular imaging technique that can be used in glaucoma diagnosis by measuring the retinal nerve fiber layer thickness. This letter presents an automated retinal layer segmentation technique for OCT images. In the proposed technique, an OCT image is first cut into multiple vessel and nonvessel sections by the retinal blood vessels that are detected through an iterative polynomial smoothing procedure. The nonvessel sections are then filtered by a bilateral filter and a median filter that suppress the local image noise but keep the global image variation ...
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    1. (23 articles) Singapore Eye Research Institute
    2. (22 articles) Tien Yin Wong
    3. (12 articles) National University of Singapore
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    Normal Macular Thickness Measurements Using Optical Coherence Tomography in Healthy Eyes of Adult Chinese Persons: The Handan Eye Study Automated Layer Segmentation of Optical Coherence Tomography Images Anterior Segment Optical Tomography Study of the Cornea and Anterior Segment in Adult Ethnic South Asian Indian Eyes Corneal Graft Evaluation Based On Optical Coherence Tomography Image Anterior Chamber Dimensions and Posterior Corneal Arc Length in Malay Eyes: An Anterior segment Optical Coherence Tomography Study Relationship Between Intraocular Pressure and Angle Configuration: An Anterior Segment OCT Study Comparison of Anterior Segment Optical Tomography Parameters Measured Using a Semi-Automatic Software to Standard Clinical Instruments Determinants of Macular Thickness using Spectral Domain Optical Coherence Tomography in Healthy Eyes: the Singapore Chinese Eye Study Optical Coherence Tomography Angiography in Myopic Patients Quantification of retinal microvasculature and neurodegeneration changes in branch retinal vein occlusion after resolution of cystoid macular edema on optical coherence tomography angiography Machining head for a laser machining device Quantitative Comparison Of Microvascular Metrics On Three Optical Coherence Tomography Angiography Devices In Chorioretinal Disease